git.sesse.net Git - ffmpeg/blob - compat/w32pthreads.h

   1 /*
   2  * Copyright (C) 2010-2011 x264 project
   3  *
   4  * Authors: Steven Walters <kemuri9@gmail.com>
   5  *          Pegasys Inc. <http://www.pegasys-inc.com>
   6  *
   7  * This file is part of Libav.
   8  *
   9  * Libav is free software; you can redistribute it and/or
  10  * modify it under the terms of the GNU Lesser General Public
  11  * License as published by the Free Software Foundation; either
  12  * version 2.1 of the License, or (at your option) any later version.
  13  *
  14  * Libav is distributed in the hope that it will be useful,
  15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  17  * Lesser General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU Lesser General Public
  20  * License along with Libav; if not, write to the Free Software
  21  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  22  */
  23
  24 /**
  25  * @file
  26  * w32threads to pthreads wrapper
  27  */
  28
  29 #ifndef LIBAV_COMPAT_W32PTHREADS_H
  30 #define LIBAV_COMPAT_W32PTHREADS_H
  31
  32 /* Build up a pthread-like API using underlying Windows API. Have only static
  33  * methods so as to not conflict with a potentially linked in pthread-win32
  34  * library.
  35  * As most functions here are used without checking return values,
  36  * only implement return values as necessary. */
  37
  38 #define WIN32_LEAN_AND_MEAN
  39 #include <windows.h>
  40 #include <process.h>
  41
  42 #include "libavutil/attributes.h"
  43 #include "libavutil/internal.h"
  44 #include "libavutil/mem.h"
  45
  46 typedef struct pthread_t {
  47     void *handle;
  48     void *(*func)(void* arg);
  49     void *arg;
  50     void *ret;
  51 } pthread_t;
  52
  53 /* the conditional variable api for windows 6.0+ uses critical sections and
  54  * not mutexes */
  55 typedef CRITICAL_SECTION pthread_mutex_t;
  56
  57 /* This is the CONDITION_VARIABLE typedef for using Windows' native
  58  * conditional variables on kernels 6.0+. */
  59 #if HAVE_CONDITION_VARIABLE_PTR
  60 typedef CONDITION_VARIABLE pthread_cond_t;
  61 #else
  62 typedef struct pthread_cond_t {
  63     void *Ptr;
  64 } pthread_cond_t;
  65 #endif
  66
  67 /* function pointers to conditional variable API on windows 6.0+ kernels */
  68 #if _WIN32_WINNT < 0x0600
  69 static void (WINAPI *cond_broadcast)(pthread_cond_t *cond);
  70 static void (WINAPI *cond_init)(pthread_cond_t *cond);
  71 static void (WINAPI *cond_signal)(pthread_cond_t *cond);
  72 static BOOL (WINAPI *cond_wait)(pthread_cond_t *cond, pthread_mutex_t *mutex,
  73                                 DWORD milliseconds);
  74 #else
  75 #define cond_init      InitializeConditionVariable
  76 #define cond_broadcast WakeAllConditionVariable
  77 #define cond_signal    WakeConditionVariable
  78 #define cond_wait      SleepConditionVariableCS
  79
  80 #define CreateEvent(a, reset, init, name)                   \
  81     CreateEventEx(a, name,                                  \
  82                   (reset ? CREATE_EVENT_MANUAL_RESET : 0) | \
  83                   (init ? CREATE_EVENT_INITIAL_SET : 0),    \
  84                   EVENT_ALL_ACCESS)
  85 // CreateSemaphoreExA seems to be desktop-only, but as long as we don't
  86 // use named semaphores, it doesn't matter if we use the W version.
  87 #define CreateSemaphore(a, b, c, d) \
  88     CreateSemaphoreExW(a, b, c, d, 0, SEMAPHORE_ALL_ACCESS)
  89 #define InitializeCriticalSection(x) InitializeCriticalSectionEx(x, 0, 0)
  90 #define WaitForSingleObject(a, b) WaitForSingleObjectEx(a, b, FALSE)
  91 #endif
  92
  93 static av_unused unsigned __stdcall attribute_align_arg win32thread_worker(void *arg)
  94 {
  95     pthread_t *h = arg;
  96     h->ret = h->func(h->arg);
  97     return 0;
  98 }
  99
 100 static av_unused int pthread_create(pthread_t *thread, const void *unused_attr,
 101                                     void *(*start_routine)(void*), void *arg)
 102 {
 103     thread->func   = start_routine;
 104     thread->arg    = arg;
 105     thread->handle = (void*)_beginthreadex(NULL, 0, win32thread_worker, thread,
 106                                            0, NULL);
 107     return !thread->handle;
 108 }
 109
 110 static av_unused void pthread_join(pthread_t thread, void **value_ptr)
 111 {
 112     DWORD ret = WaitForSingleObject(thread.handle, INFINITE);
 113     if (ret != WAIT_OBJECT_0)
 114         return;
 115     if (value_ptr)
 116         *value_ptr = thread.ret;
 117     CloseHandle(thread.handle);
 118 }
 119
 120 static inline int pthread_mutex_init(pthread_mutex_t *m, void* attr)
 121 {
 122     InitializeCriticalSection(m);
 123     return 0;
 124 }
 125 static inline int pthread_mutex_destroy(pthread_mutex_t *m)
 126 {
 127     DeleteCriticalSection(m);
 128     return 0;
 129 }
 130 static inline int pthread_mutex_lock(pthread_mutex_t *m)
 131 {
 132     EnterCriticalSection(m);
 133     return 0;
 134 }
 135 static inline int pthread_mutex_unlock(pthread_mutex_t *m)
 136 {
 137     LeaveCriticalSection(m);
 138     return 0;
 139 }
 140
 141 /* for pre-Windows 6.0 platforms we need to define and use our own condition
 142  * variable and api */
 143 typedef struct  win32_cond_t {
 144     pthread_mutex_t mtx_broadcast;
 145     pthread_mutex_t mtx_waiter_count;
 146     volatile int waiter_count;
 147     HANDLE semaphore;
 148     HANDLE waiters_done;
 149     volatile int is_broadcast;
 150 } win32_cond_t;
 151
 152 static av_unused void pthread_cond_init(pthread_cond_t *cond, const void *unused_attr)
 153 {
 154     win32_cond_t *win32_cond = NULL;
 155     if (cond_init) {
 156         cond_init(cond);
 157         return;
 158     }
 159
 160     /* non native condition variables */
 161     win32_cond = av_mallocz(sizeof(win32_cond_t));
 162     if (!win32_cond)
 163         return;
 164     cond->Ptr = win32_cond;
 165     win32_cond->semaphore = CreateSemaphore(NULL, 0, 0x7fffffff, NULL);
 166     if (!win32_cond->semaphore)
 167         return;
 168     win32_cond->waiters_done = CreateEvent(NULL, TRUE, FALSE, NULL);
 169     if (!win32_cond->waiters_done)
 170         return;
 171
 172     pthread_mutex_init(&win32_cond->mtx_waiter_count, NULL);
 173     pthread_mutex_init(&win32_cond->mtx_broadcast, NULL);
 174 }
 175
 176 static av_unused void pthread_cond_destroy(pthread_cond_t *cond)
 177 {
 178     win32_cond_t *win32_cond = cond->Ptr;
 179     /* native condition variables do not destroy */
 180     if (cond_init)
 181         return;
 182
 183     /* non native condition variables */
 184     CloseHandle(win32_cond->semaphore);
 185     CloseHandle(win32_cond->waiters_done);
 186     pthread_mutex_destroy(&win32_cond->mtx_waiter_count);
 187     pthread_mutex_destroy(&win32_cond->mtx_broadcast);
 188     av_freep(&win32_cond);
 189     cond->Ptr = NULL;
 190 }
 191
 192 static av_unused void pthread_cond_broadcast(pthread_cond_t *cond)
 193 {
 194     win32_cond_t *win32_cond = cond->Ptr;
 195     int have_waiter;
 196
 197     if (cond_broadcast) {
 198         cond_broadcast(cond);
 199         return;
 200     }
 201
 202     /* non native condition variables */
 203     pthread_mutex_lock(&win32_cond->mtx_broadcast);
 204     pthread_mutex_lock(&win32_cond->mtx_waiter_count);
 205     have_waiter = 0;
 206
 207     if (win32_cond->waiter_count) {
 208         win32_cond->is_broadcast = 1;
 209         have_waiter = 1;
 210     }
 211
 212     if (have_waiter) {
 213         ReleaseSemaphore(win32_cond->semaphore, win32_cond->waiter_count, NULL);
 214         pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
 215         WaitForSingleObject(win32_cond->waiters_done, INFINITE);
 216         ResetEvent(win32_cond->waiters_done);
 217         win32_cond->is_broadcast = 0;
 218     } else
 219         pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
 220     pthread_mutex_unlock(&win32_cond->mtx_broadcast);
 221 }
 222
 223 static av_unused int pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex)
 224 {
 225     win32_cond_t *win32_cond = cond->Ptr;
 226     int last_waiter;
 227     if (cond_wait) {
 228         cond_wait(cond, mutex, INFINITE);
 229         return 0;
 230     }
 231
 232     /* non native condition variables */
 233     pthread_mutex_lock(&win32_cond->mtx_broadcast);
 234     pthread_mutex_lock(&win32_cond->mtx_waiter_count);
 235     win32_cond->waiter_count++;
 236     pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
 237     pthread_mutex_unlock(&win32_cond->mtx_broadcast);
 238
 239     // unlock the external mutex
 240     pthread_mutex_unlock(mutex);
 241     WaitForSingleObject(win32_cond->semaphore, INFINITE);
 242
 243     pthread_mutex_lock(&win32_cond->mtx_waiter_count);
 244     win32_cond->waiter_count--;
 245     last_waiter = !win32_cond->waiter_count || !win32_cond->is_broadcast;
 246     pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
 247
 248     if (last_waiter)
 249         SetEvent(win32_cond->waiters_done);
 250
 251     // lock the external mutex
 252     return pthread_mutex_lock(mutex);
 253 }
 254
 255 static av_unused void pthread_cond_signal(pthread_cond_t *cond)
 256 {
 257     win32_cond_t *win32_cond = cond->Ptr;
 258     int have_waiter;
 259     if (cond_signal) {
 260         cond_signal(cond);
 261         return;
 262     }
 263
 264     pthread_mutex_lock(&win32_cond->mtx_broadcast);
 265
 266     /* non-native condition variables */
 267     pthread_mutex_lock(&win32_cond->mtx_waiter_count);
 268     have_waiter = win32_cond->waiter_count;
 269     pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
 270
 271     if (have_waiter) {
 272         ReleaseSemaphore(win32_cond->semaphore, 1, NULL);
 273         WaitForSingleObject(win32_cond->waiters_done, INFINITE);
 274         ResetEvent(win32_cond->waiters_done);
 275     }
 276
 277     pthread_mutex_unlock(&win32_cond->mtx_broadcast);
 278 }
 279
 280 static av_unused void w32thread_init(void)
 281 {
 282 #if _WIN32_WINNT < 0x0600
 283     HANDLE kernel_dll = GetModuleHandle(TEXT("kernel32.dll"));
 284     /* if one is available, then they should all be available */
 285     cond_init      =
 286         (void*)GetProcAddress(kernel_dll, "InitializeConditionVariable");
 287     cond_broadcast =
 288         (void*)GetProcAddress(kernel_dll, "WakeAllConditionVariable");
 289     cond_signal    =
 290         (void*)GetProcAddress(kernel_dll, "WakeConditionVariable");
 291     cond_wait      =
 292         (void*)GetProcAddress(kernel_dll, "SleepConditionVariableCS");
 293 #endif
 294
 295 }
 296
 297 #endif /* LIBAV_COMPAT_W32PTHREADS_H */